QRV04 Headphone Amp. + Red Baron v5 DAC

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Hi everyone,

I would gladly listen of your opinions regarding conecting this two pieces of DIY as i try to figure best solution.

1. Active or passive I/V stage before conecting to qrv?
2. Conecting to qrv directly to Tda1542 pin is possible? :)
3. Input caps on qrv does influence sound greatly, so i could remove the smd type and put some Mundorf for example?
4.removing completly the input caps on the qrv and put sowther transformers between dac and the headphone amp.?

Ps: sennheiser hd600 listening cans.

Thanks in advance for your help!
Alex.
 
That DAC has the usual DAC-related tinkerer-level audiophile snake oil pretty well covered, save for exotic capacitors. I am not denying that passive I/V can be useful, but that's just because you didn't put in enough filtering effort to get rid of all the high-frequency crap coming out of the converter beforehand. That sort of stuff tends to irritate bipolar input opamps in particular, a reasonably fast-slewing FET input parts tends to be beneficial.

You know, most people would probably prefer a DAC that actually works properly. Like, say, a decent onboard audio output. Or an ODAC if you want a higher level of performance and USB is your thing. Or whatever (some sort of decent PCM5102A based job maybe). DACs are mostly a solved problem though I guess some people still prefer shooting themselves in the foot.

The QRV04 is good. It allows you to experiment with some output series resistance (for a somewhat fuller bottom end on HD600s, try values of like 2x 100 ohm to 2x 200 ohm, giving 50-100 ohms). Be sure to populate the input filter components. As for the input coupling caps, I'm sure Per-Anders doesn't specify any crap-quality components, plus you could still generously oversize things even if you were forced to use MLCC ceramics. If your DAC output is AC-coupled, you could even replace them with simple wire links / 0-ohm resistors. I would never use any of these ridiculously huge Mundorf speaker crossover film caps in such a place, just some decent WIMAs or Panasonics.

I see the power supply does not use capacitors from the regulators' ADJ pins to ground. Those may be worth adding, like 10 µF (25+V) electrolytic. It shouldn't matter much in terms of noise, but regulation / transient behavior should improve.
 
Hi,
10x a lot for great info.

I will try to get that smd Evox Riva caps that P-A is recommending. (although is hard to find them)

Second, you're probably(sure) right, but my pleasure to tinker and plant all components on a pcb is greater than buying a fully built dac.

BTW, you're right i'm going to use USB. WaveIO seems a good choice?

About supply, all powered by shunt regulators. It's going to be a big box....and a LOT of tinkering! :)

Rgs,
Alex.
 
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